Workpieces, including food products, are cut or otherwise portioned into smaller portions by processors in accordance with customer needs. Also, excess fat, bone, and other foreign or undesired materials are routinely trimmed from food products. It is usually highly desirable to portion and/or trim the workpieces into uniform sizes, for example, for steaks to be served at restaurants or chicken fillets used in frozen dinners or in chicken burgers. Much of the portioning/trimming of workpieces, in particular food products, is now carried out with the use of high-speed portioning machines. These machines use various scanning techniques to ascertain the size and shape of the food product as it is being advanced on a moving conveyor. This information is analyzed with the aid of a computer to determine how to most efficiently portion the food product into optimum sizes. For example, a customer may desire chicken breast portions in two different weight sizes, but with no fat or with a limited amount of acceptable fat. The chicken breast is scanned as it moves on an infeed conveyor belt and a determination is made through the use of a computer as to how best to portion the chicken breast to the weights desired by the customer, so as to use the chicken breast most effectively.
Portioning and/or trimming of the workpiece can be carried out by various cutting devices, including high-speed liquid jet cutters (liquids may include, for example, water or liquid nitrogen) or rotary or reciprocating blades, after the food product is transferred from the infeed to a cutting conveyor. Once the portioning/trimming has occurred, the resulting portions are off-loaded from the cutting conveyor and placed on a take-away conveyor for further processing or, perhaps, to be placed in a storage bin.
Portioning machines of the foregoing type are known in the art. Such portioning machines, or portions thereof, are disclosed in prior patents, for example, U.S. Pat. Nos. 4,962,568 and 5,868,056, which are incorporated by reference herein. As typical, the portioning machine includes an infeed conveyor having a moving, solid belt that slides over a support structure. The infeed conveyor belt is driven at a selected speed by a drive motor. The drive motor can be composed of a variable speed motor to thus adjust the speed of the infeed belt. The workpieces are carried on the infeed conveyor belt to be scanned and then are transferred to a cutting conveyor, typically constructed with a conveyor belt of open mesh metal material. The workpieces are cut/portioned/trimmed while on the cutting conveyor.
The workpieces are first carried by the infeed conveyor past a scanning station, where the workpieces are scanned to ascertain selected physical parameters, for example, their size and shape, and then determine their weight, typically by utilizing an assumed density for the workpieces. In addition, it is possible to locate discontinuities (including voids), foreign material, and undesirable material in the workpiece, for example, bones or fat in a meat portion.
The scanning can be carried out utilizing a variety of techniques, including a video camera to view a workpiece illuminated by one or more light sources. Light from the light source is extended across the moving conveyor belt to define a sharp shadow or light stripe line, with the area forwardly of the transverse beam being dark. When no workpiece is being carried by the infeed conveyor, the shadow line/light stripe forms a straight line across the conveyor belt. However, when a workpiece passes across the shadow line/light stripe, the upper, irregular surface of the workpiece produces an irregular shadow line/light stripe as viewed by a video camera directed downwardly on the workpiece and the shadow line/light stripe. The video camera detects the displacement of the shadow line/light stripe from the position it would occupy if no workpiece were present on the conveyor belt. This displacement represents the thickness of the workpiece along the shadow line/light stripe. The length of the workpiece is determined by the length of belt travel that shadow lines/light stripes are created by the workpiece. In this regard, an encoder is integrated into the infeed conveyor, with the encoder generating pulses at fixed distance intervals corresponding to the forward movement of the conveyor.
In lieu of a video camera, the scanning station may instead utilize an x-ray apparatus for determining the physical characteristics of the workpiece, including its shape, mass, and weight. X-rays may be passed through the object in the direction of an x-ray detector. Such x-rays are attenuated by the workpiece in proportion to the mass thereof. The x-ray detector is capable of measuring the intensity the x-rays received thereby after passing through the workpiece. This information is utilized to determine the overall shape and size of the workpiece, as well as the mass thereof. An example of such an x-ray scanning device is disclosed by U.S. Pat. No. 5,585,603, incorporated by reference herein.
The data and information measured/gathered by the scanning devices is transmitted to a computer, preferably on board the portioning apparatus, which records the location of the workpiece on the conveyors as well as the shape and other parameters of the workpiece. With this information, the computer determines how to optimally cut or portion the workpiece at the portioning station, and the portioning may be carried out by various types of cutting/portioning devices including high-pressure liquid jets as disclosed in U.S. Pat. Nos. 4,875,254, 5,365,816, and 5,868,056. Other types of cutting devices may be utilized, including band saws, reciprocating saws, circular saws, guillotine knives, and lasers. Workpieces can be portioned in accordance with desired portion sizes, maximum fat content or thickness and other parameters.
Most of the portioned food products eventually undergo a cooking process before they are served or packaged. The size, shape, and other parameters of each portion affect how much cook time is required to properly cook (e.g., heat) the portion. In many cases, it is desirable that each of the multiple portioned pieces has a cook time within acceptable limits, so that they all can be cooked for an anticipatable period of time, and thus can be properly prepared in a controlled preparation system, having minimal variability. In the present description, the term “cook time” is used to refer to the amount of time required to properly or desirably cook a food product. Currently, however, portioning machines cut food products without regard to cook-time considerations for the resulting pieces. Therefore, those pieces that fail cook-time checks need to be rejected and discarded, after they have already been cut from the original product, creating undue waste. A need exists for a portioning machine that cuts products into pieces in accordance with various cook time considerations.
The present invention provides improvements to portioning machines of the foregoing general construction, to address the above-addressed need.